Feb.25 (GMM) The car being tested by Toro Rosso this week is a cross between the 2015 and 2016 machines, driver Carlos Sainz has revealed.

Firstly, the car is being run at Barcelona in an interim plain-blue livery, after the Faenza team ran out of time amid the hurry to switch to Ferrari power.

Max Verstappen joked to De Telegraaf newspaper that it's like "a woman without makeup. But beauty is on the inside."

The blue Toro Rosso, however, has also seemed to not be very fast so far, but the Dutch driver insists he is not worried.

"Our goal was to drive many laps, and we succeeded," said Verstappen.

"If we too had used soft tyres and done other things we would be a second and a half faster and the situation would look very different," he explained.

"That all comes later. No, I'm definitely not worried," Max insisted.

Indeed, it now emerges that the car doing laps this week is in fact not the 2016 Toro Rosso, but last year's chassis running as a test mule for new parts.

"The car is a mixture of the 2015 and 2016 cars," Verstappen's teammate Sainz said. "At the moment we are working on reliability, the speed comes next week.

"Here, it's a STR10 with STR11 parts that has been made for this test only," he explained.

The full STR11 and its livery will be unveiled prior to the second and final Barcelona test next week.

"Knowing how late the engine decision was made last year," Sainz said, "I am amazed that the team managed to get the car ready for the first winter test.

"How they did it is beyond me, but not only did they do it, it is running reliably.

"I don't even know what position I finished today or what compounds the others have used. It is next week that we will see the STR11 in full and I can say something about the performance," added Sainz.